Utility of P19 Gene-Silencing Suppressor for High Level Expression of Recombinant Human Therapeutic Proteins in Plant Cells

Background: The potential of plants, as a safe and eukaryotic system, is considered in the production of recombinant therapeutic human protein today; but the expression level of heterologous proteins is limited by the posttranscriptional gene silencing (PTGS) response in this new technology. The use of viral suppressors of gene silencing can prevent PTGS and improve transient expression level of foreign proteins. In this study, we investigated the effect of p19 silencing suppressor on recombinant human nerve growth factor expression in Nicotiana benthamiana. Materials and Methods: The p19 coding region was inserted in the pCAMBIA using NcoI and BstEII recognition sites. Also, the cloned synthesized recombinant human NGF (rhNGF) fragment was cloned directly into PVX vector by ClaI and SalI restriction enzymes. The coagroinfiltration of rhNGF with p19 viral suppressor of gene silencing was evaluated by dotblot and SDSPAGE. The amount of expressed rhNGF protein was calculated by AlphaEaseFC software. Results: Coagroinfiltration of hNGF with P19 suppressor showed about fortyfold increase (8% total soluble protein (TSP)) when compared to the absence of P19 suppressor (0.2%TSP). Conclusion: The results presented here confirmed that the use of P19 gene silencing suppressor derived from tomato bushy stunt virus (TBSV) could efficiently increase the transient expression of recombinant proteins in Nicotiana benthamiana manifold.